/* * A generic kernel FIFO implementation. * * Copyright (C) 2009 Stefani Seibold <stefani@seibold.net> * Copyright (C) 2004 Stelian Pop <stelian@popies.net> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * */ #include <linux/kernel.h>#include <linux/module.h>#include <linux/slab.h>#include <linux/err.h>#include <linux/kfifo.h>#include <linux/log2.h>#include <linux/uaccess.h> static void _kfifo_init(struct kfifo *fifo, void *buffer,		unsigned int size){	fifo->buffer = buffer;	fifo->size = size; 	kfifo_reset(fifo);} /** * kfifo_init - initialize a FIFO using a preallocated buffer * @fifo: the fifo to assign the buffer * @buffer: the preallocated buffer to be used. * @size: the size of the internal buffer, this has to be a power of 2. * */void kfifo_init(struct kfifo *fifo, void *buffer, unsigned int size){	/* size must be a power of 2 */	BUG_ON(!is_power_of_2(size)); 	_kfifo_init(fifo, buffer, size);}EXPORT_SYMBOL(kfifo_init); /** * kfifo_alloc - allocates a new FIFO internal buffer * @fifo: the fifo to assign then new buffer * @size: the size of the buffer to be allocated, this have to be a power of 2. * @gfp_mask: get_free_pages mask, passed to kmalloc() * * This function dynamically allocates a new fifo internal buffer * * The size will be rounded-up to a power of 2. * The buffer will be release with kfifo_free(). * Return 0 if no error, otherwise the an error code */int kfifo_alloc(struct kfifo *fifo, unsigned int size, gfp_t gfp_mask){	unsigned char *buffer; 	/*	 * round up to the next power of 2, since our 'let the indices	 * wrap' technique works only in this case.	 */	if (!is_power_of_2(size)) {		BUG_ON(size > 0x80000000);		size = roundup_pow_of_two(size);	} 	buffer = kmalloc(size, gfp_mask);	if (!buffer) {		_kfifo_init(fifo, NULL, 0);		return -ENOMEM;	} 	_kfifo_init(fifo, buffer, size); 	return 0;}EXPORT_SYMBOL(kfifo_alloc); /** * kfifo_free - frees the FIFO internal buffer * @fifo: the fifo to be freed. */void kfifo_free(struct kfifo *fifo){	kfree(fifo->buffer);	_kfifo_init(fifo, NULL, 0);}EXPORT_SYMBOL(kfifo_free); /** * kfifo_skip - skip output data * @fifo: the fifo to be used. * @len: number of bytes to skip */void kfifo_skip(struct kfifo *fifo, unsigned int len){	if (len < kfifo_len(fifo)) {		__kfifo_add_out(fifo, len);		return;	}	kfifo_reset_out(fifo);}EXPORT_SYMBOL(kfifo_skip); static inline void __kfifo_in_data(struct kfifo *fifo,		const void *from, unsigned int len, unsigned int off){	unsigned int l; 	/*	 * Ensure that we sample the fifo->out index -before- we	 * start putting bytes into the kfifo.	 */ 	smp_mb(); 	off = __kfifo_off(fifo, fifo->in + off); 	/* first put the data starting from fifo->in to buffer end */	l = min(len, fifo->size - off);	memcpy(fifo->buffer + off, from, l); 	/* then put the rest (if any) at the beginning of the buffer */	memcpy(fifo->buffer, from + l, len - l);} static inline void __kfifo_out_data(struct kfifo *fifo,		void *to, unsigned int len, unsigned int off){	unsigned int l; 	/*	 * Ensure that we sample the fifo->in index -before- we	 * start removing bytes from the kfifo.	 */ 	smp_rmb(); 	off = __kfifo_off(fifo, fifo->out + off); 	/* first get the data from fifo->out until the end of the buffer */	l = min(len, fifo->size - off);	memcpy(to, fifo->buffer + off, l); 	/* then get the rest (if any) from the beginning of the buffer */	memcpy(to + l, fifo->buffer, len - l);} static inline int __kfifo_from_user_data(struct kfifo *fifo,	 const void __user *from, unsigned int len, unsigned int off,	 unsigned *lenout){	unsigned int l;	int ret; 	/*	 * Ensure that we sample the fifo->out index -before- we	 * start putting bytes into the kfifo.	 */ 	smp_mb(); 	off = __kfifo_off(fifo, fifo->in + off); 	/* first put the data starting from fifo->in to buffer end */	l = min(len, fifo->size - off);	ret = copy_from_user(fifo->buffer + off, from, l);	if (unlikely(ret)) {		*lenout = ret;		return -EFAULT;	}	*lenout = l; 	/* then put the rest (if any) at the beginning of the buffer */	ret = copy_from_user(fifo->buffer, from + l, len - l);	*lenout += ret ? ret : len - l;	return ret ? -EFAULT : 0;} static inline int __kfifo_to_user_data(struct kfifo *fifo,		void __user *to, unsigned int len, unsigned int off, unsigned *lenout){	unsigned int l;	int ret; 	/*	 * Ensure that we sample the fifo->in index -before- we	 * start removing bytes from the kfifo.	 */ 	smp_rmb(); 	off = __kfifo_off(fifo, fifo->out + off); 	/* first get the data from fifo->out until the end of the buffer */	l = min(len, fifo->size - off);	ret = copy_to_user(to, fifo->buffer + off, l);	*lenout = l;	if (unlikely(ret)) {		*lenout -= ret;		return -EFAULT;	} 	/* then get the rest (if any) from the beginning of the buffer */	len -= l;	ret = copy_to_user(to + l, fifo->buffer, len);	if (unlikely(ret)) {		*lenout += len - ret;		return -EFAULT;	}	*lenout += len;	return 0;} unsigned int __kfifo_in_n(struct kfifo *fifo,	const void *from, unsigned int len, unsigned int recsize){	if (kfifo_avail(fifo) < len + recsize)		return len + 1; 	__kfifo_in_data(fifo, from, len, recsize);	return 0;}EXPORT_SYMBOL(__kfifo_in_n); /** * kfifo_in - puts some data into the FIFO * @fifo: the fifo to be used. * @from: the data to be added. * @len: the length of the data to be added. * * This function copies at most @len bytes from the @from buffer into * the FIFO depending on the free space, and returns the number of * bytes copied. * * Note that with only one concurrent reader and one concurrent * writer, you don't need extra locking to use these functions. */unsigned int kfifo_in(struct kfifo *fifo, const void *from,				unsigned int len){	len = min(kfifo_avail(fifo), len); 	__kfifo_in_data(fifo, from, len, 0);	__kfifo_add_in(fifo, len);	return len;}EXPORT_SYMBOL(kfifo_in); unsigned int __kfifo_in_generic(struct kfifo *fifo,	const void *from, unsigned int len, unsigned int recsize){	return __kfifo_in_rec(fifo, from, len, recsize);}EXPORT_SYMBOL(__kfifo_in_generic); unsigned int __kfifo_out_n(struct kfifo *fifo,	void *to, unsigned int len, unsigned int recsize){	if (kfifo_len(fifo) < len + recsize)		return len; 	__kfifo_out_data(fifo, to, len, recsize);	__kfifo_add_out(fifo, len + recsize);	return 0;}EXPORT_SYMBOL(__kfifo_out_n); /** * kfifo_out - gets some data from the FIFO * @fifo: the fifo to be used. * @to: where the data must be copied. * @len: the size of the destination buffer. * * This function copies at most @len bytes from the FIFO into the * @to buffer and returns the number of copied bytes. * * Note that with only one concurrent reader and one concurrent * writer, you don't need extra locking to use these functions. */unsigned int kfifo_out(struct kfifo *fifo, void *to, unsigned int len){	len = min(kfifo_len(fifo), len); 	__kfifo_out_data(fifo, to, len, 0);	__kfifo_add_out(fifo, len); 	return len;}EXPORT_SYMBOL(kfifo_out); /** * kfifo_out_peek - copy some data from the FIFO, but do not remove it * @fifo: the fifo to be used. * @to: where the data must be copied. * @len: the size of the destination buffer. * @offset: offset into the fifo * * This function copies at most @len bytes at @offset from the FIFO * into the @to buffer and returns the number of copied bytes. * The data is not removed from the FIFO. */unsigned int kfifo_out_peek(struct kfifo *fifo, void *to, unsigned int len,			    unsigned offset){	len = min(kfifo_len(fifo), len + offset); 	__kfifo_out_data(fifo, to, len, offset);	return len;}EXPORT_SYMBOL(kfifo_out_peek); unsigned int __kfifo_out_generic(struct kfifo *fifo,	void *to, unsigned int len, unsigned int recsize,	unsigned int *total){	return __kfifo_out_rec(fifo, to, len, recsize, total);}EXPORT_SYMBOL(__kfifo_out_generic); unsigned int __kfifo_from_user_n(struct kfifo *fifo,	const void __user *from, unsigned int len, unsigned int recsize){	unsigned total; 	if (kfifo_avail(fifo) < len + recsize)		return len + 1; 	__kfifo_from_user_data(fifo, from, len, recsize, &total);	return total;}EXPORT_SYMBOL(__kfifo_from_user_n); /** * kfifo_from_user - puts some data from user space into the FIFO * @fifo: the fifo to be used. * @from: pointer to the data to be added. * @len: the length of the data to be added. * @total: the actual returned data length. * * This function copies at most @len bytes from the @from into the * FIFO depending and returns -EFAULT/0. * * Note that with only one concurrent reader and one concurrent * writer, you don't need extra locking to use these functions. */int kfifo_from_user(struct kfifo *fifo,        const void __user *from, unsigned int len, unsigned *total){	int ret;	len = min(kfifo_avail(fifo), len);	ret = __kfifo_from_user_data(fifo, from, len, 0, total);	if (ret)		return ret;	__kfifo_add_in(fifo, len);	return 0;}EXPORT_SYMBOL(kfifo_from_user); unsigned int __kfifo_from_user_generic(struct kfifo *fifo,	const void __user *from, unsigned int len, unsigned int recsize){	return __kfifo_from_user_rec(fifo, from, len, recsize);}EXPORT_SYMBOL(__kfifo_from_user_generic); unsigned int __kfifo_to_user_n(struct kfifo *fifo,	void __user *to, unsigned int len, unsigned int reclen,	unsigned int recsize){	unsigned int ret, total; 	if (kfifo_len(fifo) < reclen + recsize)		return len; 	ret = __kfifo_to_user_data(fifo, to, reclen, recsize, &total); 	if (likely(ret == 0))		__kfifo_add_out(fifo, reclen + recsize); 	return total;}EXPORT_SYMBOL(__kfifo_to_user_n); /** * kfifo_to_user - gets data from the FIFO and write it to user space * @fifo: the fifo to be used. * @to: where the data must be copied. * @len: the size of the destination buffer. * @lenout: pointer to output variable with copied data * * This function copies at most @len bytes from the FIFO into the * @to buffer and 0 or -EFAULT. * * Note that with only one concurrent reader and one concurrent * writer, you don't need extra locking to use these functions. */int kfifo_to_user(struct kfifo *fifo,	void __user *to, unsigned int len, unsigned *lenout){	int ret;	len = min(kfifo_len(fifo), len);	ret = __kfifo_to_user_data(fifo, to, len, 0, lenout);	__kfifo_add_out(fifo, *lenout);	return ret;}EXPORT_SYMBOL(kfifo_to_user); unsigned int __kfifo_to_user_generic(struct kfifo *fifo,	void __user *to, unsigned int len, unsigned int recsize,	unsigned int *total){	return __kfifo_to_user_rec(fifo, to, len, recsize, total);}EXPORT_SYMBOL(__kfifo_to_user_generic); unsigned int __kfifo_peek_generic(struct kfifo *fifo, unsigned int recsize){	if (recsize == 0)		return kfifo_avail(fifo); 	return __kfifo_peek_n(fifo, recsize);}EXPORT_SYMBOL(__kfifo_peek_generic); void __kfifo_skip_generic(struct kfifo *fifo, unsigned int recsize){	__kfifo_skip_rec(fifo, recsize);}EXPORT_SYMBOL(__kfifo_skip_generic);